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Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi
Dimensional stability and decay resistance of hot-melt self-bonded particleboard by surface benzylated pine chips
1991 - IRG/WP 3652
Akamatsu (Pinus densiflora Sieb. et Zucc: Japanese red pine) particles were pretreated with 40% NaOH solution and benzylated with benzyl chloride, and the surface of particle was converted into meltable materials. Hot-melt self bonded particleboard having smooth and high glossiness surface was prepared by hot pressing at 150°C and 1.96 MPa without using any conventional adhesives. Dimensional stability and decay resistance of the benzylated particleboard were evaluated. Particleboards made of benzylated particles having more than 38% of weight percent gain (WPG) showed that dimensional stability and decay resistance were superior to the conventional particleboard made by using phenolformaldehyde resin as a binder, because hydroxyl groups of wood were substituted by hydrophobic benzyl groups with benzylation. Though bending strength of the board was a little lower than control board due to the damage of benzylated particles during benzylation, its internal bonding strength was very high, because the hot-melting strengthened the inter-particle bonding.
M Kiguchi, K Yamamoto
Effects of acetylation on the dimensional stability and decay resistance of kenaf (Hibiscus cannabinus L.) fiberboard
1996 - IRG/WP 96-40059
The objective of this study was to investigate the influence of the acetylation treated kenaf fiber, Phenol formaldehyde resin content level, and three fungi species on the dimensional stability and decay resistance of high density non wood composition boards. A standard ASTM method was used to evaluate weight loss and thickness change. The linear shrinkage and expansion of each species were also determined. All specimens were exposed to decay chambers for 16 weeks. Test results indicated that most of the main factors significantly influence the thickness, length changes, and decay resistance of the high density kenaf fiberboards.
P Chow, T Harp, R Meimban, J A Youngquist, R M Rowell
The decay resistance of chemically modified aspen composites to the white rot fungus Coriolus versicolor (L.) Quelet
1998 - IRG/WP 98-40122
Chemical modification of Aspen wood (Populus tremula L.) in the form of solid wood, veneers and sawdust was undertaken by a two step procedure consisting of esterification with maleic anhydride (MA) and subsequent oligoesterification with MA and glycidyl methacrylate (GMA) or allyl glycidyl ether (AGE). Modified wood was thermoplastic and was thermally formed by hot-pressing to produce veneer or solid wood samples with smooth glossy surfaces, while plastic-like wafers were obtained by hotpressing modified sawdust. Chemical modification alone was shown to enhance the biological resistance of Aspen to decay by Coriolus versicolor. In addition, hot-pressing enhanced decay resistance of both unmodified wood and esterified wood veneer samples, although no improvement was found by hot pressing oligoesterified wood. The most effective treatment for the improvement of decay resistance was chemical modification of the sawdust in conjunction with hot-pressing. A microscopic examination of chemically modified and control samples following exposure to the fungus showed more extensive colonisation and decay in untreated, unpressed samples.
M C Timar, A J Pitman, M D Mihai
Physical and biological properties of albizzia waferboards modified with cross-linking agents
1995 - IRG/WP 95-40043
Chemically-modified low-density waferboards with cross-linking agents were produced using a fast-growing species of hardwood albizzia (Paraserienthes falcata Becker) as a raw materials and isocyanate resin as a glue adhesive. For the chemical modification, the vapor-phase formalization of the boards and the pad-dry-cure treatment of wafers with cross-linking agents were employed. The vapor-phase formalization was conducted for 5, 10 and 24 hours using tetraoxane as a source of formaldehyde, and the pad-dry-cure treatments with glutaraldehyde and ethyleneurea compound (DMDHEU) were made after impregnation of their 5 and 10% aqueous solutions of each chemical. Sulfur dioxide was used as a catalyst in both treatments. About 70% of antiswelling efficiency (ASE) was gained in all treated boards irrespective of reaction time or solution concentration. All treated boards were very stable to water soaking even in the 2-hour boiling on thickness swelling as well as linear expansion. Laboratory tests with brown-rot and white-rot fungi revealed that decay was completely suppressed in formaldehyde-treated boards, and small losses in weight were counted in other treated boards. All treated boards were also effective in resisting to the attack by the destructive termite Coptotermes formosanus.
S Yusuf, Y Imamura, M Takahashi, K Minato
An attempt to evaluate wood resistance against fungal decay in non-sterile conditions by measuring the variation of resistance to bending test
1988 - IRG/WP 2308
The main object of this work was to determine the variation of strength on large test specimens of wood (800 x 45 x 45 mm³) when exposed to accelerated fungal attacks close to natural conditions, out of test vessels. The modulus of elasticity (MOE) and the modulus of rupture (MOR) have been assessed. Thereby, the natural resistance of the wood species to fungal decay, the efficiency of preservative as well as the treatment applied are discussed. The wood tested is a guianese secondary species (Couma guianensis). The fungi tested are two guianese strains of brown and white rot. The exposure time is 12 weeks. No mould contamination has been recorded by use of a selective fungicide. The results obtained show that it is possible to infest in nonsterile conditions large wood specimens. Furthermore, modulus of rupture appears to be the most reliable criterion. The investigation, that requires limited equipment and staff could be performed in any tropical research station as it has been done at CTFT, French Guiana center.
L N Trong
Decay resistance of wood removed from poles treated with Trichoderma
1989 - IRG/WP 1386
Wood blocks removed from a distribution pole previously treated with a biological control product (Binab FYT pellets) were exposed in soil block tests to selected basidiomycetes. The blocks were removed from regions of poles where Trichoderma colonization had been confirmed by extensive sampling and computer mapping of microbial inhabitants. The results indicate that material from pole interiors colonized by Trichoderma is able to resist decay by Lentinus lepideus and Antrodia carbonica. Any decay prevention was lost however when the wood was steam sterilized prior to exposure to the basidiomycetes. The implications of the results for the use of biological control of internal decay in creosoted poles is briefly discussed.
A Bruce, B King, T L Highley
Biological Durability of Laminated Veneer Lumber from Durable and Non-Durable Wood Species
2005 - IRG/WP 05-10567
Laminated Veneer Lumber (LVL) was laboratory manufactured using veneers from decay and non decay resistant species in order to evaluate changes in the durability as a result of the LVL manufacturing process, and to test if the mixing of decay resistant species and non decay resistant species can improve durability. Laboratory soil block test and field test were conducted. The durability of solid wood was comparable to that of LVL made using the same species. For LVL made using veneer from durable and non-durable wood species, durability was improved when two faces and one core veneers were from decay resistant species.
P Nzokou, J Zyskowski, S Boury, D P Kamdem
Questionnaire pour la préparation de fiches monographiques pour les champignons lignivores
1972 - IRG/WP 103 F
Efficacy of anhydrides as wood protection chemicals - II. Performance against soft rot fungi
1998 - IRG/WP 98-30174
Pine sapwood modified with various anhydrides and with butyl isocyanate was tested for its resistance to soft rot decay. Small stakes were exposed for 20 months in unsterile soil in a fungal cellar test. Wood modified with butyl isocyanate performed better than any of the anhydrides tested, with a threshold level of protection (less than 3% weight loss) at 12% weight percent gain (WPG). Stakes acetylated to 15% WPG did not give complete protection against soft rot. Stakes modified with alkenyl succinic anhydride showed increasing resistance to soft rot with WPG up to about 10% WPG, above which no further improvements were evident. Succinic anhydride and phthalic anhydride treated stakes showed little or no noticeable protection.
S C Forster, M D C Hale, G R Williams
Model questionnaire for preparation of monographic cards for wood-destroying fungi
1972 - IRG/WP 103
Monographic card: Coniophora puteana (Schum. ex Fr.) Karst. (Second draft)
1978 - IRG/WP 171
Combined effects of the treatment of wood with formaldehyde
1978 - IRG/WP 3117
Treatment of fibrous materials with reagents in a vapor phase is neither new nor unique. Numerous examples exist in literature of vapor phase experiments on cellulose fibers and fabrics, and on wood. For many years the textile research and industry have used vapor phase processes for the treatment of textiles. The chemical modification of cellulose is based on different types of reactions e.g. esterification, alkylation, resin formation or polymerization, monomer grafting and crosslinking. Vapor phase treatment of wood offers certain potential advantages over the conventional liquid phase wood impregnation. The higher mobility of low molecular weight compounds in the gaseous state ensures a rapid, uniform and homogeneous distribution throughout the wood structure. The vapor phase treatment of wood is also a better approach from the standpoint of cell wall penetration. Bulking, which takes place in the cell wall only, means that less chemicals are required and that the final weight of the composite is limited. Furthermore, due to the low viscosity of a gas, the application of a lower pressure differential remains possible. Within the framework of a wood improvement programme carried out at the Laboratory of Wood Biology and Wood Technology (University of Ghent, Belgium) the treatments were based on the impregnation of wood with liquid synthetic monomers and with gaseous formaldehyde. The results of the hygroscopic and dimensional behaviour of the wood-plastic-combinations have been published previously. Other papers deal with the physical and chemical interactions between the synthetic products and the natural polymers of the cell wall. This contribution will be restricted to the treatment of wood with formaldehyde in the gaseous state.
M Stevens, J Schalck
A summary of tests and practical experiences with the Pilodyn wood testing instrument
1980 - IRG/WP 282
This paper presents a summary of the reports, tests and practical experiences with the Pilodyn wood tester not only, however, concerning poles but also in other fields such as standing trees, sawn timber etc. The principle of the Pilodyn is a spring-loaded pin which is fired into the object and the depth to which the pin penetrates is correlated to physical and mechanical properties of the object.
Decay resistance of resin treated wood
1999 - IRG/WP 99-30206
Selected natural resin systems were evaluated for their potential as wood protecting agents according to standard test procedures. As indicated by the European standard EN 599 both a Basidiomycete test according to EN 113 and a ENV 807 soil bed test were carried out. Six resin treatments were tested using 3 concentration or treatment levels. Using the biocidal activity criteria as usually applied for wood preservatives it became obvious that resin treatments do not comply to the standard requirements. None of the resin treatments tested allowed the establishment of toxic limits when all Basidiomycete fungi were considered. Four resin systems showed a clear impact of retention. The functional relationship of the percentage mass loss to the resin retention was examined. Based on this function the retention levels corresponding with specific mass loss levels were calculated for each fungus. Treatment levels are proposed taking into account the envisaged utilisation under European hazard class 3 (EN 335) and the mass loss criteria for wood species belonging to natural durability class 3.
J Van Acker, A J Nurmi, S M Gray, H Militz, C Hill, H Kokko, A O Rapp
Final draft of a monographic card for Pole Fungus A, L Harmsen, Rigidoporus vitreus (Fr.) Donk according to the 'Model Questionnaire for preparation of monographic cards for wood-destroying fungi'
1978 - IRG/WP 178
Monographic information on Serpula (Merulius) lacrymans (Schum. ex Fr.) S. F. Gray, according to the 'Model Questionnaire for preparation of monographic cards for wood-destroying fungi'
1978 - IRG/WP 170
J Segmüller, O Wälchli
Studies on the preservation of structrual plywood - Part 1: Decay resistance of structural plywood
1974 - IRG/WP 238
The weight loss and the decreases in the compression strength and in the modulus of elasticity were measured to determine the decay resistance of structural plywood (lauan). Test pieces (50x25xA mm³) were exposed to the wood destroying fungi (Coriolus versicolor and Coriolellus palustris) for 2-3 or 2-4 months. After exposure, the measurement of the compression strength was carried out on the pieces of different thickness (A = 6,12 and 18 mm) and different fibre direction of the face veneer (0°, 45° and 90° to the long side of the test piece). The results obtained were as follows: 1.: The weight loss was small. The greatest weight loss was 9.4% on decaying by Coriolellus palustris for 4 months. 2.: The decreases in the compression strength and in the modulus of elasticity were greater than the weight loss. On decaying by Coriolellus palustris for 4 months, the ratio of decrease of the compression strength was 75% (6 mm - 0°). 3.: For differences of the thickness and of the fibre direction, the weight loss and the decreases the modulus of elasticity in the compression strength and in the modulus of elasticity showed tendencies in order 0° > 45° > 90° and 6 > 12 > 18 mm. 4.: According to the experiment, the face veneer is liable to be easily attacked by the wood destroying fungi, but the decrease in the compression strength was great. So, the face veneer and the cross section should be protected with preservatives for structural use.
K Minami, Y Kenjo, S Sugiyama
The Pilodyn instrument as a non-destructive tester of the shock resistance of wood
1978 - IRG/WP 2107
A new non-destructive shock resistance tester, the PILODYN, has been developed. The instrument measures the fracture surface area created by a constant amount of energy. It operates by shooting a blunt pin into wood by an exact amount of energy. The penetration depth is read on a scale. A wide field of application is open to a non-destructive shock resistance tester such as: 1) assessment of the residual strength of poles decaying from the outside; 2) laboratory evaluation of biodeteriorated wood; 3) the state of wood foundations and woody pilework; 4) degree of chemical decomposition of wood; 5) degree of thermal decomposition of wood; 6) measurement of the density (strength) of standing trees; 7) measurement of the density (strength) of sawn timber; 8) production control of wood based panel boards. A review of existing test results as well as new results are presented containing items 1, 6 and 7. An evaluation of the potential of the PILODYN is attempted.
Monographic information on Serpula (Poria) incrassata according to the "Model Questionnaire for preparation of monographic cards for wood-destroying fungi"
1980 - IRG/WP 160
J G Palmer, W E Eslyn
Biological degradation resistance of pine wood treated with dimethylol compounds
1989 - IRG/WP 3528
The study reports the increase of dimensional stability and biological degradation resistance of pine wood (Pinus sylvestris L) after impregnation with dimethyloldibydroxyethyleneurea. Decay resistance was determined according to BS 838:961. Nearly complete protection against Coniophora puteana, (Schum.ex Fr. Karst) weight loss of 2-3% was shown when modification, expressed as weight gain, exceeded 15%. Resistance to biological attack of modified wood is speculated to be due to modification of the wood components and cross linking with dimethyloldihydroxyethyleneurea.
C L Videlov
Decay, decayed wood and the Shigometer
1980 - IRG/WP 281
A L Shigo
Decay resistance of high performance biocomposites based on chemically modified fibres
1998 - IRG/WP 98-40120
Different partners within the framework of a European research project produced high performance biocomposites aiming at the utilisation of board materials as durable products both in dimensional and biological degrading circumstances. This paper summarises test data, which indicate the potential of board materials produced with modified fibre material. The chemical modifications applied cover a range of technologies, which were selected for scaling up experiments. Acetylation, as well as alternative methods like maleiation, phthalylation, succinylation, oxidation and silylation were investigated. Fibre source, density variation and the use of several types of glues were parameters of the total set-up. Basidiomycete testing was carried out using specific methodology for board materials elaborated in CEN standardisation committees.
V Rijckaert, J Van Acker, M Stevens
Monographic information on Serpula incrassata (Berk. and Curt.) Donk
1980 - IRG/WP 1128
J G Palmer, W E Eslyn
First draft of a monographic card for Gloeophyllum abietinum (Bull. ex Fr.) Karst
1973 - IRG/WP 116